It has long been known that it is desirable to prevent static electricity build-up on polymeric materials. For example, in the case of textile materials such as carpets, static electricity builds up when people walk on the carpet, thereby resulting in uncomfortable electric shocks when the walker touches a grounded object. Furthermore, when such static electricity builds up on polymeric material associated with computing equipment (e.g., cabinets and other enclosures), loss of data on electromagnetic media, damage to equipment, and a fire hazard may result.
It has long been an object to increase the conductivity of polymeric materials to some degree, in order to permit the dissipation of the static electric charges. For this purpose, such materials as quaternary ammonium salts, monoacyl glycerides, monoalkyl phosphates and various metalocenes and other surface-active materials have been proposed and/or heretofore employed.
Unfortunately, the foregoing surface-active materials are often only soluble in polymeric materials to a very limited extent and have comparatively low decomposition temperatures, so that during polymer processsing they are effectively destroyed. In addition, it is not uncommon for known surfactant type antistatic agents to "bloom", that is, migrate to the surface of molded articles. Naturally, such blooming reduces the enhancement of the volume conductivity of the polymeric object and renders the antistatic agent of little value, once the surface has been abraded by wear.
The known metalocene based conductive additives primarily based on cobaltocene and other transition metal biscyclopentadiene derivatives suffer from the disadvantages of requiring relatively high proportions (5-20 wt. %) of expensive reagent in order to achieve effective conductivity enhancement, with consequent significant physical property impairments and often intense product discoloration. Such metalocene conductivity enhancers as are presently known cannot be used at temperatures in excess of 200.degree. C. because of their high reactivity and thermal instability, thus preventing their use in polymer systems requiring higher process, application or use temperatures.